Passage IV

Three Studies were conducted to investigate factors that affect wind erosion.

Study 1

Samples of 3 different soils (A-C)were collected from a study area and each was analyzed for sand, silt, and clay particle content and water content (see Table 1).

Study 2

Another sample of each soil was dried in an oven for 24 hours, crushed, and passed through a screen with 0.84 mm openings. Each sample was used to fill its own 7 mm deep porous metal tray. Each tray was placed in a wind tunnel. A piece of white tape was placed at the downwind end of the tray (see Figure 1).

The wind speed was gradually increased until particles from the soil first began to collect on the white tape. This threshold wind speed was recorded for each sample.

The procedure described above was repeated, except that sand particles (an abrasive), which had been dyed green, were added at a constant rate to the moving air. The results are shown in Table 2.

Study 3

A third sample of each soil was prepared as in Study 2. Each tray was placed in shallow water for 24 hours to saturate the sample. Each tray was then placed in the' wind tunnel and exposed to an 8.5 m/sec wind. Once the win had dried the top of the soil sample sufficiently, soil particles began to appear on the white tape. At that time, the water content o f the top 1 mm of the soil sample was determined. This procedure was repeated 3 more times: first adding dyed sand to the 8.5 m/sec wind, then using a 13 m/sec wind, without and then with added sand. The results are shown in Figure 2.